Efficiently and accurately determining the presence or amount of an analyte in a biological sample has become increasingly important. Often, an assay must be performed in a clinical laboratory to obtain an accurate quantitative measurement. When the protocol requires the addition of measured amounts of sample and reagents, a skilled technician must usually perform the assay to guarantee a reliable result. The measurement of an analyte in a biological fluid plays an increasingly important role in the treatment and therapy of numerous medical conditions. The ability to quickly make a qualitative or quantitative determination, in the home or doctor's office, of the presence or amount of an analyte in a sample is of great interest.
An assay which may be accurately and efficiently performed outside of the clinical laboratory would provide results which may be immediately addressed by the physician and patient. To guarantee the accuracy of the assay determination, the system should have an integral control or standard by which the assay determination may be verified. The control would assure that the device was operated as intended, that there has been no spoilage or contamination of the device such as through improper storage and handling, and that the results may be relied upon. A system which may be used in a doctor's office or in the home should have a simple protocol which does not require the measurement of either sample or reagents. Systems have been developed for performing numerous assays outside of the clinical laboratory. Nevertheless, there is continuing interest in providing improved and alternative methods to those which are presently generally available.
In addition, the devices will be for single use and be disposed of after the use. For this purpose, the device must be capable of being efficiently manufactured in an economic manner and be relatively small, so as to minimize the disposal volume. The manufacturing process should be simple to minimize failures and enhance reproducibility of the devices, so that there is a low failure rate during production.
The determination of cholesterol levels in blood provides one example where there is an interest in an accurate and reliable system which provides immediate results. There has been an increasing awareness that the level of total blood cholesterol, primarily the LDL fraction, should be maintained within a specific range to promote the health of the individual and reduce the risks of coronary artery disease. Recognition of individuals with high blood cholesterol levels is important, since the cholesterol level may be controlled by adjusting the diet and/or administering cholesterol lowering drugs. A system which may be easily and conveniently used by an individual at home to monitor his cholesterol level would provide a significant tool in aiding the individual to maintain a healthy blood cholesterol level. The use of such a system in the doctor's office would also be particularly useful for efficiently identifying and monitoring the treatment of individuals with high blood cholesterol.
The monitoring of blood cholesterol levels provides one example of where there is a need for a reliable system which may be used outside of the clinical laboratory. The determination of the presence or amount of numerous other analytes in a biological sample is also of great interest.